We’re big fans of health apps, those clever little programs that convert your smartphone or tablet into a stress reliever, workout buddy, healthy eating log, even a personal assistant that tracks your blood pressure, blood sugar, vision, sleep and a lot more. But with 40,000-plus to choose from, how do you know where to start?

Good question. App stores don’t have authoritative medical reviewers — yet — to make sure health apps live up to their claims. And apps are big business ($1.4 billion by the end of this year!), and that means big hype.

Fortunately, researchers are starting to study health-related apps; a medical journal devoted to mHealth (that’s “mobile health”!) just started up. And you may have seen the recent headlines about the U.S. Food and Drug Administration’s interest in putting medical-app developers through the same approval process as medical devices (pacemakers and coronary stents, for example).

But for now, we’re going to try to help you make the best choices. Start your hunt with these mSmart (short for “mobile smart”) strategies. Then take some of our favorite apps for a test drive.

No. 1: Set your health goal, then look for an app to help you. The best apps complement the work you do every day to stay healthy. Like your sneakers or the veggie steamer in your kitchen cabinet, an app can’t do the work for you; they’re tools. So start with a goal in mind. Maybe you want to keep track of your weekly walking totals (how many steps? 10,000 a day!), or would you rather count your daily servings of fruit and veggies? Then look for an app that can help.

No. 2: Don’t believe the hype. Immediate weight loss! End that 20-year smoking habit today! If an app promises to deliver results that sound too good to be true, they probably are. Don’t waste your time and money.

No. 3: Read users’ reviews. Let other app lovers give you valuable clues about whether a program delivers. PCworld.com and the American Dietetic Association (eatright.org/appreviews/) can give you good insights; and the Apple, Blackberry and Android marketplaces offer interesting user-generated reviews. For the truly motivated: Find the developer’s name in the app store or company website, then check if it has designed other apps. Did it work with experts on this one?

No. 4: Test-drive a couple. No app suits everybody. We suspect that maybe as many as 30 percent of people who try any one app stick with it. So plan on test-driving a couple. Since many are free and many more cost less than a dollar to download, this won’t break your budget. The right app for you should be easy and convenient to use, and should deliver promised results.

Five Free Apps We Love

Wondering what we like? Start with these:

S.O.S. This free app for Android phones, developed by one of us (Dr. Oz) with the American Red Cross and Sharecare, gives you step-by-step instructions for dealing with a variety of emergencies, including choking, broken bones, strokes and allergic reactions.

Go! To Sleep. This unique app — from Dr. Mike’s Cleveland Clinic — reveals your personal “sleep score,” rating the quality of your sleep and showing you how caffeine, alcohol, exercise, relaxation and other factors help or hurt your slumber.

MyQuitLine. This one offers expert advice and connects you — by phone or by live help — with a trained quitting-smoking counselor at the National Cancer Institute Quitline.

Glucose Buddy. This app lets people with diabetes track blood sugar levels and A1Cs, and creates graphs showing blood sugar levels over time and printouts for your doc. It also can track your diet, exercise routines and medications.

Calorie Counter by FatSecret. This four-star-rated food and diet app uses your daily calorie goal to help you set up healthy meal plans. You can keep track of what you eat and your exercise routines, and it lets you compare what works and what doesn’t with other users.

Mehmet Oz, M.D. is host of “The Dr. Oz Show,” and Mike Roizen, M.D. is Chief Medical Officer at the Cleveland Clinic Wellness Institute. For more information go to www.RealAge.com.